1. Field Of The Invention:
The apparatus of the present invention relates to prefabricated composite drain structures, particularly useful in draining land areas such as golf courses. More particularly, the present invention relates to a sleeve-like coupling for coupling a lateral drainage line onto the principal drainage structure in a prefabricated composite drainage structure.
2. General Background:
The proper drainage of rain water from various types of land usage situations, such as buildings, streets, parks, recreational areas, is crucial in maintaining the integrity of the land for proper usage. In the present state of the art, one of the most effective means of drainage, for example, away from foundations of buildings, is through the use of prefabricated composite drainage structures which generally include an outer fabric such as a geotextile layer that accommodates the flow of water through the fibers yet filters out nearly all soil particles being carried along the flow of water. There is further included an inner core which consists of a flexible polystyrene core, which is presently covered under U.S. Pat. Nos. 3,563,038 and U.S. Pat. No. 3,654,765 which consists of a flexible polystyrene core member having a plurality of raised portions throughout the surface of the core layer so that the surrounding fabric does not collapse against the inner core as the water is filtered therethrough, yet the spaced apart raised members provide a flow space therebetween for flow of water out of the core member structure following the flow through the fabric layer. This prefabricated composite drain for major structure land areas has become a known replacement for the aggregate or "French Drains".
Another important use of the composite drainage structure in addition to the drainage of water around large structures such as buildings, is to utilize the drainage structure in a somewhat different mode for drainage of land areas, more particularly for drainage of golf courses or the like. What is provided is that the internal flexible polystyrene core member is cut into strips approximately 3 inches to 1 foot high, with 6 inches being the most common. The strips of polystyrene are placed within a geotextile fabric sleeve, with the sleeve covering the continuous strength of the strip. A ditch or the like is dug in the land along the border of the land to be drained in the appropriate water collection support points, and the structure is laid on edge within the ditch, and would be back filled with sand or native soils. Therefore, as water flows, due to rain, irrigation or the like, would force the water through the geotextile filter, to the inside of the polystyrene core down to the drainage point in the land, the hydro static pressure would force the water through the geotextile outer fabric filter layer, to the inside of the strip in the flexible polystyrene core. Once the water has entered the free flowing area it continues to flow along the plastic core with no internal pressure to force it back to the outside. As long as there prevails a minimum slope of 1%, water will continue to flow to an outlet point such as a collection basin, outlet pipe or larger drainage canal.
In order to drain wide areas as efficiently as possible a system of lateral drains are used to collect water from areas outside of the collection areas serviced by the main line. These laterals funnel the water into one main drain which is used to carry all of the collected water to the collection basin, outlet pipe, or larger drainage canal. It has been learned that a series of lateral drains flowing into the main drain structure provides additional water to be channeled into the main structure, and at the point where the water flow enters the main drain structure from the lateral drain structure, the velocity of water flow can be increased if the water from the lateral drain enters the main drain at the correct angle, and enters without any interference. In attempting to form a proper juncture at the point where the lateral drain structures feed into the main drain structure, a continuing problem has arisen. Due to the fact that both the main drain line and the lateral lines have internal polystyrene core with the filter fabric sleeve surrounding it, it is necessary then that the water from the lateral drain lines flow easily into the main drain line. This is accomplished basically in two methods.
The first method would encompass having the one end portion of the lateral drain line angularly abut the outer surface of the fabric filter, without actually breaking into the core area. The result would be that as the water flow flows out of the lateral drain line and into the surrounding media it must then be reabsorbed through the filter fabric of the main drain line so that it passes into the water collection space of the core members and likewise flows along the main flow. This presents two problems. One being that water flow must be interrupted in order to be reabsorbed through the fabric surrounding the main drain line prior to continuing on its flow. Secondly, the feed of the lateral must necessarily be left open to allow the water to exit freely. This makes it very possible for dirt to naturally enter this lateral line at this point. As the water table rises and falls, over a period of time, this could severally clog the lateral drain.
The second method is to cut a window in the fabric of the main line, and insert an end portion of the lateral drain line angularly into that window so that the main drain line makes direct contact into the internal flow spaces of the internal core member. This method also has its shortcomings. One short-coming is the fact that the fabric layer or the core member of the lateral line often times projects into the interspaces between the projections of the core member and impedes the flow of water through the main line acting as a barier in that flow space. If this problem can be overcome, the second serious problem is that the window in the main drain line, while accommodating a structure of the lateral drain, also allows foreign particles, which have been henceforth filtered by the fabric, to enter the water flow, for example, dirt or the like, and ultimately impede the flow to the point where it can become blocked as dirt would accumulate between the projections in the core member.
Therefore, what is needed is a method or structure for accommodating the juncture point of a lateral flow line into a main flow line for solving the problems as were discussed earlier.